Installation guide

Virtual machine timer management with libvirt
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Without the acpid package, the Red Hat Enterprise Linux 6 guest does not shut down when the virsh
shutdown command is executed. The virsh shutdown command is designed to gracefully shut
down virtualized guests.
Using virsh shutdown is easier and safer for system administration. Without graceful shut down
with the virsh shutdown command a system administrator must log into a virtualized guest
manually or send the Ctrl-Alt-Del key combination to each guest.
Other virtualized operating systems
Other virtualized operating systems may be affected by this issue. The virsh shutdown
command requires that the guest operating system is configured to handle ACPI shut down
requests. Many operating systems require additional configuration on the guest operating system
to accept ACPI shut down requests.
Procedure 24.1. Workaround for Red Hat Enterprise Linux 6
1. Install the acpid package
The acpid service listen and processes ACPI requests.
Log into the guest and install the acpid package on the guest:
# yum install acpid
2. Enable the acpid service
Set the acpid service to start during the guest boot sequence and start the service:
# chkconfig acpid on
# service acpid start
The guest is now configured to shut down when the virsh shutdown command is used.
24.11. Virtual machine timer management with libvirt
Accurate time keeping on virtualized guests is a key challenge for virtualization platforms. Different
hypervisors attempt to handle the problem of time keeping in a variety of ways. Libvirt provides
hypervisor independent configuration settings for time management, using the <clock> and <timer>
elements in the domain XML. Note that not all options are supported for all hypervisors. The domain
XML can be edited using the virsh edit command. See Editing a guest's configuration file for
details.
<clock>
The clock element is used to determine how the guest clock is synchronized with the host clock. The
clock element has the following attributes:
•
offset
Determines how the guest clock is offset from the host clock. The offset attribute has the following
possible values: